The classically trained musician performed alongside rock legends the Rolling Stones this week – and he's gearing up to do it all again this weekend.

Professor Tregear has been secretly preparing for the Victorian legs of the band's On Fire tour in Australia alongside the Consort of Melbourne choir, a gig he has had to keep quiet for close to seven months.

He lead the 23-strong choral group in a performance of You Can't Always Get What You Want in front of 24,000 people at Melbourne's Rod Laver Arena on Wednesday night.

The group will return to the stage in front of potentially twice as many people for an outdoor performance at Hanging Rock near Mount Macedon in Victoria.

Professor Tregear said the Rolling Stones had engaged choirs across Australia to perform the beginning of the song, which opens with a choral solo.

"I don't suspect many heads of music departments have performed with the Rolling Stones," he laughed.

"It's the first time, I believe, they've performed it with a live choir. With classical music, [the 24,000-strong crowd] is probably a one-off – I don't think that will happen again."

Professor Tregear said a former UK-based colleague, choral personality Suzi Digby, had helped line up choirs for the international tour.

The once-in-a-lifetime opportunity enabled the choral group to rock along to the show's first few songs in the mosh pit directly in front of the stage.

But Professor Tregear had to hide his excitement from colleagues right up until the choir's opening night in Melbourne.

"You want to tell people – 'I'm performing with the Rolling Stones' is not a line I suspect any us will use ever again," he said.

"They were magnificently engaging. We were not expecting to draw any attention [but] the band were very warm. They give all choirs a very good credit at the end ... and a wonderful roar from the 24,000 people."

Professor Tregear said he had always been open to left-of-field performances, combining his classical training with pop and rock performances, and encouraged his Canberra students to keep an open mind.

"If I had been told when I was younger that my classical music degree would lead to performing with the Rolling Stones I would have said, 'yeah, right'.

"In a sense the music industry is very small. We're much closer than many would think across these genre divides."